Lab 6. Morphology Part 2: Insect Internal Anatomy

In this lab you will dissect a freshly killed cockroach and learn to recognize various internal organs and organ systems.

Objectives

Main objectives of this lab are to help you:

1.   distinguish among different types of tissues within an insect’s body
2.   learn the location and appearance of internal organs in a typical insect

Activities

1. Refer to Resources

Before and during lab, make sure to utilize these resources:

• Roach Guts Gallery (pictures of structures we will look at in lab)
• Lab 6 Handout (step-by-step instructions for dissecting, and what to look for)
• Audio Slide Show  (step-by-step description of the dissection process)
• Orkin Virtual Roach (interactive drawn images of roach)

2. Materials for Lab

See the list at the bottom of this page

3. Use Patience

Most of the structures described in this lab will be best viewed with the aid of a stereomicroscope or a hand lens.  A good dissection requires time and patience — make small cuts and don’t remove a piece of tissue unless you know what it is.

4. Prepare for Dissection

DE STUDENTS:  if you do not attend a lab period, follow these instructions for collecting cockroaches and setting up dissecting trays.

a. Use dissecting scissors to cut off all legs, wings, and antennae.

b. Use dissecting scissors to cut (follow dotted lines in figure below) near the edge of tergites (the “back”), being very careful not to probe too deeply with the scissors. Leave the last abdominal tergum and the head uncut.

c. Pin the specimen ventral side (the “belly”) down in a dissecting dish as in the figure above. 

d. Fill the dish with enough tap water to cover the body.

e. Determine the gender of your roach (see first image in Roach Guts Gallery)

5. Conduct Dissection

a. Pull each tergite up with forceps and with a pin or sharp blade carefully tease away tissues underneath to remove.  An analogy is pulling the plastic cover off the top of a frozen TV dinner.

b.  Once all the cut tergites and pronotum are removed, follow the instructions in the Lab 6 Handout to complete the dissection and identify all of the structures you will be tested on in the first Lab Practical Exam.

Materials

You will need the following for this lab:

1. Smartphone or computer, to access class website
2. Dissecting tools (insect pins, dissecting scissors, fine-point forceps, dissecting dish or tray, stereomicroscope or hand lens) (all provided in lab)
3. Patience